Process for refining hydrocarbons with boron trifluoride followed by a solvent



. A. P. STUART PROCESS FOR REFINING HYDROCARBGNS WITH BQRON Oct. 16.,1956 TRIFLUORIDE FOLLOWED 'BY A SOLVENT Filed June 30, 1955 JBMOl bugqsoJSMOl uogoouxg Jexgw T T Y m k V my sm P. T D m A L A L B m R q A 4 AIIKum 2 220 55:00:25

United States Patent Archibald P. Stuart, Media, Pa., assignor to SunOil Company, Philadelphia, Pa., a corporation of New Jersey ApplicationJune 30, 1955, Serial No. 519,116

7 Claims. (CL 196-24) This invention relates to a process for refininghydrocarbon materials containing one or more undesirable impurities.More particularly, the invention relates to a process for removingnon-hydrocarbons, such as sulfur compounds, from admixtures thereof withhydrocarbons, such as petroleum oil fractions containing sulfurcompounds.

Various processes for removing non-hydrocarbons from hydrocarbonmaterials have heretofore been described. It is known, for example, totreat hydrocarbon oils with Bib, either alone or as a complex withanother material such as an oxygenated organic compound. After the BE;treatment such processes generally require a neutralization step, whichis accomplished by washing the treated hydrocarbon material with anaqueous caustic solution or by treating with ammonia gas. Suchprocesses, however, while effective for removing a portion of thenonhydrocarbons have generally been unsatisfactory in that a refinedproduct that is stable to oxidation is not obtained.

it has now been found that a refined, stable hydrocarbon product can beobtained from a mixture of a hydrocarbon material with one or morenon-hydrocarbon materials by treating the mixture with BFs so that asludge is formed, separating the sludge from the system, and extractingthe separated hydrocarbon material with a solvent for the reactionproduct of BF and non-hydrocarbons.

The accompanying figure is a flow diagram illustrating an embodiment ofthe process of the invention and is more fully described hereinafter.

In accordance with the invention, a hydrocarbon material mixed with oneor more non-hydrocarbon materials is treated with ER. This treatmentconverts a large proportion of the non-hydrocarbons to materialsinsoluble in the hydrocarbon material. The so-formed sludge is separatedfrom the body of the hydrocarbon material. The hydrocarbon material isthen extracted by contacting with a solvent for the reaction product ofBFs and the non-hydrocarbons. The extracted hydrocarbon material is thenpreferably washed with water and dried. It has been found that theproduct of this process is highly refined and stable against oxidation.

While it is not known with certainty why the process of the invention isremarkably efiEecti-ve in producing a highly refined, stable hydrocarbonproduct, it is believed that, while a. large proportion of the reactionproducts of BF?, and the non-hydrocarbons is insoluble in thehydrocarbon material, at least a portion of such reaction products issoluble in the hydrocarbon material. soluble reaction products are notseparable as sludge and, with heretofore used processes, appear toremain as impurities in the hydrocarbon material. In the process of thepresent invention, these soluble reaction products are removed from thehydrocarbon material by extraction with a solvent for such reactionmaterials. In this manner, a hydrocarbon product more highly refined andsta- Such r 2,767,120 Patented Oct. 16, 1956 ble than products ofheretofore known processes is obtained.

Hydrocarbon materials containing non-hydrocarbon impurities which can beemployed in the process of the invention are the petroleum hydrocarbonfractions such as gasoline, naphtha, kerosene, fuel oil, gas oil andlubricating oil fractions Which contain minor quantities ofnon-hydrocarbons such as sulfur, oxygen or nitrogen compounds, ormixtures thereof. The quantity of non-hydro: carbons present in suchfractions will generally be from about .05 to 8% and usually from .1 to2%. Such petroleum hydrocarbon oils may have been subjected to var-i oustreatments prior to their use in the process of the invention. Forexample, oils which have been subjected to solvent extraction, acidtreatment, clay contacting, and the like, can advantageously beemployed.

The quantity of BF3 to employ is advantageously varied in accordancewith the quantity of non-hydrocarbons present in the hydrocarbonmaterial being treated. While an excess is not deleterious, the quantityof BFa should be maintained Within the range of from 0.01 to 10% byweight of the oil, and usually will be within the range of from 0.05 to5% by weight :of the oil. The time, temperature and pressure to employduring the BFs contacting do not appear critical. Usually a time of from'5 to 60 minutes will be employed because of practical considerations.The pressure can be sub-atmospheric, atiITlOSPhBIlC orsuper-atmospheric, but is advantageously from atmospheric to 200 p. s.i. g. Preferably ambient temperature is used, but a relatively lowtemperature, say about 30 F, or a relatively high temperature, say about300 F., can be advantageously used in some instances... An elevatedtemperature is advantageously used, for example, to lower the viscosity:of a heavy oil for the BF:.

treatment.

The solvent to employ in the process should be etfeo. tive fordissolving the reaction product of BFs and the; non-hydrocarbon ornon-hydrocarbons present in the hy-' drocarbon materials, and should besubstantially immiscible with the hydrocarbon material. Acetic acid isthe preferred solvent, but other relatively low molecular: weight acidshaving not more than 4 carbon atoms, such as formic acid, propionic acidand butyric acid, can be used. Other solvents can be substituted inwhole or in part for the described acids such as the niu'iles of thedescribed acids, esters having not more than a total of 8 carbon atomssuch as methyl acetate, ethyl acetate, methyl propionate and ethylpropionate, alcohols having a total of not more than 6 carbon atoms suchas methanol, ethanol, butanol and hexanol, and amides having a total ofnot more than 6 carbon atoms, preferably di methyl formamide. Thequantity of solvent employed should be at least suflicient to forma-separate phase when admixed with a hydrocarbon material. A quantity offrom 0.5 to 10 volumes of solvent or more per volume of hydrocarbonmaterials gives good results, but it is preferred to employ at least 2volumes of solvent per volume of hydrocarbon material. I

The solvent extraction can be performed by conventional means, such ascontinuously by use of an extraction tower, or batchwise by intimatelycontacting the solvent and hydrocarbon material, allowing two phases toseparate, and separating the phases by decanting. While it is generallyunnecessary, it is advantageous in some instances, after the solventextraction step, to wash' the hydrocarbon materials with water andfollow the washing step with a drying step. The Washing step is:conveniently accomplished by intimately contacting water with thehydrocarbon materials continuously in an extraction tower, or batchwiseby mechanical mixing, lowing the water to form a separate phase, anddecanting. The drying step is conveniently accomplished by passing aninert gas such 'as flue gas or nitrogen through the washed hydrocarbonmaterials, preferably at an elevated temperature, but other drying meansknown to the art can be employed if desired. J Attention is now directedto the accompanying figure which is a flow diagram illustratinganembodirnent of the process of the invention. The hydrocarbon chargeinaterial is introduced into the process through line 1 and passes intomixer 2, wherein the hydrocarbon charge is admixed with BFs introducedthrough line 4. The resulting admixture is passed through line '5 tosettler 6, wherein sludge formed by the action of BB upon thenon-hydrocarbon constituents of the hydrocarbon charge settles out andis removed from the proces through line 8.; Line 9 and valve 10 areprovided to release excess BFs, if any, from the reaction'mixture, andto provide for pressure control if desired. From-settler 6 thehydrocarbon material is passed through line 11 into extraction tower 12,wherein it is contacted with acetic acid introduced through line 14. Thehydrocarbon material leaves extraction tower 12 through line 15 and ispassed to washing tower 16. Acetic acid is removed from extraction tower12 through line 18 and is passed to a purification step 19 whereinmaterials extracted by the acetic acid are removed through line 20.Acetic acid is recycled through the system through lines 21 and 14. The

purification of acetic acid as shown by 19 is conveniently accomplishedby distillation, but other means can be employed if desired. carbons arecontacted with water introduced through line '22. The water, containingany residual acetic acid from the extraction tower, leaves Washing tower16 through line 24. The washed hydrocarbons are passed through line 25to drier 26 wherein moisture is removed. This can be accomplished byheating and/or by passing an inert gas through the hydrocarbon material,or by other means if desired.- The refined hydrocarbon product of theprocess is removed from drier 26 through line 28. In the flow diagram,as above described, valves, pumps,

meters, and the like, the location and operation of which will beapparent to those skilled in the art, have been largely omitted.

Other embodiments of the process can be employed if desired. Forexample, it is unnecessary to completely separate sludge formed with theBF; prior to the solvent.

extraction step, i. e., at least a portion of the sludge can remain withthe hydrocarbon charge to the extraction step. It is necessary, however,in accordance with the invention, to treat with BF3 to form a sludgeprior to contacting the hydrocarbon material with the solvent.

The following examples illustrate the process of the invention, in whichparts refers to parts by weight:

s 788.3 parts of a solvent refined lubricating oil was treated with 11.3parts of. BFs. The lubricating oil charge had a boiling range of from536 F. to 745 F., a viscosity of about 57 SUS at 100 F. and about 33.9SUS at 210 F., and contained about 0.14% by weight sulfur compounds(calculated as sulfur), about 0.004% by weight nitrogen compounds(calculated as nitrogen), and about 0.097% by weight oxygen compounds(calculated as oxygen). The BF3 treatment was performed by introducingthe BFs into the oil contained in a pressure vessel. The pressure, dueto the addition of BF3,

In washing tower 16, the hydro-' was yellow, from the third extractionwas slightly yellow, and from the remaining extractions was clear. Theoil product, designated as B, had an oxygen content of below 0.01% byweight (calculated as oxygen) and a sulfur content of about 0.08% byweight (calculated as sulfur), and was testedasdescribed below.

0.02% by weight dibutyl-p-cresol, a known oxidation inhibitonwas added'to both A' and B and the inhibited.

products subjected'tooxidation... Interfacial tension between water andoil was used to measure the extent of oxidation of the oil (ASTMmethodD971-50). The

oxidation procedure was to pass air for 96 hoursat a) rate of 7 ml. ofair (measured at ambient temperature.

and pressure) per ml. .of oil per minute through a 7O varied from about165 to 150 p. s. i. g. Ambient temperature, about 70 F., was used. Aftercontacting the oil and BF3 for about 15 .minutes, the excess BFa wasreleased and 'the sludge formed was separated by cen- The resulting BFstreated oil was divided into two parts, hereinafter designated Part Aand fPart B.

The acidity of part A was neutralized with ammonia.

.partsof glacial acetic acid. The acid from the first extraction wasdark brown, from the second extraction ml. oil sample maintained at 200F. in contact with 25 cm. of iron wire (B. & S. No. 19) and 25 cm. ofcopper Wire (B. & S. No. 18). Prior to oxidation both A and B exhibitedan interfacial tension of about 42.

Results obtained were as follows:

Product Interracial tension to the BFs treatment, designated as Part Cand fPart' Part C was treated with BFs and subsequently extracted with aglacial acetic acid, in accordance with the process of the invention asabove described; the product is designated below as C.

Part D extracted with glacial acetic acid seven times using thequantities and procedure as above described, the product is designatedbelow as D, and was the hydrocarbon charge material not treated withBFa, but which was extracted with glacial acetic acid.

Both C and D, to which were added 0.02% by weight dibutyl-p-cresol, weretested by ASTM method D943-54 modified by humidifying the oxygen bypassage through water (instead of using drying oxygen) prior to itsintroduction into the test system, by adding 6 cc. (instead of 60 cc.)of water to the oil, and by introducing the oxygen into the oil layer(instead of the water layer). Results show the life of the oils to be asfollows:

Product Life (hours) When other hydrocarbon materials containingnonhydrocarbons, and when other solvents for the reaction products ofBFs and non-hydrocarbons are employed, as above described, resultssubstantially equivalent to those above described are obtained.

The invention claimed is:

1. Process for desulfurizing a petroleum hydrocarbon fraction whichcomprises contacting a petroleum hydrocarbon fraction containing sulfurcompounds with BFs to form a sludge, separating said sludge from thehydrocarbon fraction, extracting the separated hydrocarbon fraction witha solventselected from the group consisting of organic acids having notmore than 4 carbon atoms, the nitriles of said-acids, esters having atotal of not more than 8 carbon atoms, alcohols having a total of notmore than 6 carbon atoms, and amides having a total V of not more than 6carbon atoms.

2. Process for desulfurizing a petroleum hydrocarbon oil which comprisescontacting said oil with from 0.01 to 10% by weight BFa to form asludge, separating the sludge from the reaction mixture, extracting theresulting reaction mixture with a solvent selected from the groupconsisting of organic acids having not more than 4 carbon atoms, thenitriles of said acids, esters having a total of not more than 8 carbonatoms, alcohols having a total of not more than 6 carbon atoms, andamides having a total of not more than 6 carbon atoms, washing theextracted oil with Water and drying the washed oil.

3. Process according to claim 2 wherein said solvent is acetic acid.

4. Process according to claim 2 wherein said solvent is dimethylformamide.

5. Process according to claim 2 wherein said solvent is propionic acid.

6. Process according to claim 2 wherein said solvent is butyric acid.

7. Process according to claim 2 wherein said solvent is methyl acetate.

References Cited in the file of this patent UNITED STATES PATENTS2,343,841 Burk Mar. 7, 1944

1. A PROCESS FOR DESULFURIZING A PETROLEUM HYDROCARBON FRACTION WHICHCOMPRISES CONTACTING A PETROLEUM HYDROCARBON FRACTION CONTAINING SULFURCOMPOUNDS WITH BF3 TO FORM A SLUDGE, SEPARATING SAID SLUDGE FROM THEHYDROCARBON FRACTION, EXTRACTING THE SEPARATED HYDROCARBON FRACTION WITHA SOLVENT SELECTED FROM THE GROUP CONSISTING OF ORGANIC ACIDS HAVING NOTMORE THAN 4 CARBON ATOMS, THE NITRILES OF SAID ACIDS, ESTERS HAVING ATOTAL OF NOT MORE THAN 8 CARBON ATOMS, ALCOHOLS HAVING A TOTAL OF NOTMORE THAN 6 CARBON ATOMS, AND AMIDES HAVING A TOTAL OF NOT MORE THAN 6CARBON ATOMS.